High-speed revolving field-magnet



UNITED STATES PATENT OFFICE.

REINHOLD RDENBERG,

TION OF GERMANY.

NEAR BERLIN, GERMANY, ASSIGNOR GERMANY, A. CORPORA- HIGH-SPEED REVOLVING FIELD-MAGNET.

Application led September To all Ywhom it may concern.:

Be it known that I, REINHoLn RDEN- nene, a German citizen, and resident of Charlottenburg, near Berlin, (Jrernany, have linvented certain new and useful Improvecreasing their velocity.

The .present invention relates to a construction, which will allow of increasing the Y circumferential velocity beyond the hereto- 'fore customary limit of about 100 meters per second.

lilith the object of allowing of increasing the velocity of high-speed armatiires,`it has been proposed to reduce the masses `by substituting for the copper conductors such made of aluminum. This has been done with armatures having an annular winding.

However, the construction of these armatures cannot bc applied to lfield-magnets, be-

cause the mechanical strains which are obtained with armature constructions, remain,

in consequence of the more favorable conditions with armatures, far below the limit which is reached1 in the known designs, with field-magnets.

.According to the resent invention it is possible to further increase the output of any of the` above referred to turbo-alternator types, if the selection of the materials employed in the construction of its field-magnets is made from dillerent points of view than were hitherto customary, and, in particular, formed the basis for the above-mentioned armature designs. ln designing such machines the choice of the conductor material was the first step, and this conductor material was so chosen, that it showed a minimum loss. The mechanical strain exerted by the weight of the winding on the machine, then, determined the maximum speed admissible, and therewith also the maximum output of the respective type.

Specification of Letters Patent.

Patented May 3, 1921.

3o, 1915. Serial No. 53,343. Thus, the two factors, specific resistance and density, were taken separately into consideration. If, however, these two items are jointly considered, essentially more favor able results may be obtained without the losses being increased, as will be apparent from the following.

At the high velocities in question with field-magnets, constructions, such as have been hitherto employed in armatures, are not applicable.` Therefore only such constructions will come into consideration for the present invention, in which the centrifual force acting on the conductor, is received, not by the latter, but by special holding devices.

n the accompanying drawing a fieldmagnet of this kind is exemplified in diagram.

Figure 1 is a longitudinal section, such a field-magnet.

Fig. 2 is a cross-section on the line A-B in Fig. 1.

The field-magnetis composed of an iron body 1, provided with journals 2. The niiddle raised art of said iron body l is provided with 4longitudinal grooves 3, in which the winding of conductor material 6 is placed. At their upper edges, in the circumference of the iron body 1, these rooves are undercut, and closed by means o dovetail keys 4, which are driven into the said undercuttings. These keys serve to hold the windin in the grooves, and prevent its being das ed out therefrom under action of the centrifugal force, when the field-magnet revolves at its high speed.

For further securing and holdingr the end windings 6 caps 5 are fitted by suitable means over the preferably tapered ends of the iron body 1 and the eud windings thereon.

For further securing the conductor winding bandages of a suitable materiel may be wrapped around the field-magnet and the aforementioned keys.

If, now, with such construction, we coinpare two exciter coils of different materials indicated in the following by the indices 1 and 2, res ectively, which are so dimensioned that, at t e same excitation, they will show the same loss in energy, this loss may be expressed, for the respective materials, by the following formula:

where g, and g, are chosen in accordance with the specific resistance of the niaterials employed.

With equal length per turn the qnotient of the weights g, and g, of the two' windings is proportional the roducts otsection and density (c) of sai `windings; tlilns By substituting, accordingrto Vformula (3) the equivalent for-1 we obtain the formula If, new, We assume that the values with the index 1 represent the valuesA for copper, we will obtain, for a diierent material more favorable results than for copper-,provided the product o f thefspeciiic gravity specific resistance forthis respective material is smaller than the correspo ding p 'rpd'f uct of the respective values or copper.

kg.cm, and the speelfic .resistance is 1.75- 103 'em. This product is equal to A .the velocita, un

1.56.10? kg. {Lem-2. Therefore the product of speciiicgravity andl specific. resistance of a' material superiorto coppenmust be less than 1.56-10" kg. from.

Materials suitable for the purpose are, above all, aluminum and various alloys of aluminum and cop er.

The lower, there ore, at the same loss, the weight thus obtained for the exciter-winding ma e of the res ective material, the higher with it the output of the respective t e of machine may be raised. A. considera e increase is obtained for aluminum, for which the density is=2.710*3 kg, cmf', the specific resistance =2.8710- Qcm, and the product of` both=0i775 10-8 kg.9cm' thus only half as great as that for co' per.

IfV or example, in the fieldmagnet shown in the drawing, the winding were made of copper, 'the holding devices (teeth, keys, bandages and ca s) would, at the velocity mentioned, not e able to bear the strain irrespective of the dimensions given to the said parts,

vThis is made possible, however, by the present invention if the conductor material is selected from such points of View as have hereinbefore been dis-russed'and explained.

Having thus described myA invention I claim as; new anddesire to secureby-Letters Patent of theUnited States i 41. `In electrical alternators in combination a field ma et designed to revolve atan extraordinarily high speed, slots in said magnet,co'nductors placed Ainto said slots, and holding'devices for said conductors 'adapted to take -up the entire centrifu al'strain exerted upon said conductors wile the magnet revolves, the product of density and specific resistance of the conductor material lreingr smaller than that of copper.

2. In electric-alternators' in combination a field ma et designed to revolveat an extraordinarily high s'pee'd,'slots in Said magnet, aluminum'conductors laced into said slots andholding devices or saildieonductors adapted to take up the entirerentri ugal strain exerted 'upon said conductors w ile the magnet revolves.

REINHLD RUDENBERG. 

